Method and Apparatus for Region of Interest Video Coding Using Tiles and Tile Groups

ABSTRACT

Systems, methods, and instrumentalities are disclosed relating to region of interest (ROI) video coding using tiles and tile groups. An encoded video sequence including a plurality of tiles may be received. The plurality of tiles may be divided into one or more tile groups. Signaling indicating parameters of the one or more tile groups may be received. A tile group of the one or more tiles groups may be decoded and a picture relating to the decoded tile group may be displayed. The decoded tile group may overlap the ROI. The ROI may correspond to the displayed picture and the displayed picture may be a portion of the encoded video sequence. The tile groups that do not overlap the ROI may not be decoded.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/702,676, filed Sep. 18, 2012, the content of which ishereby incorporated by reference herein.

BACKGROUND

High Efficiency Video Coding (HEVC) may achieve 2× compression ratio atthe same subjective quality as H.264/AVC. With the explosive growth ofsmart phones and tablets, mobile video applications, such as but notlimited to video streaming, video chat, video sharing, and gaming, havebecome part of people's daily life. The explosive growth of videotraffic on mobile devices may put a significant demand on the wirelessnetwork infrastructure, even with the implementations of 4G mobilenetworks. HEVC may be utilized in the mobile space to alleviate some ofthe bandwidth problems. The utilization of Ultra HDTV (U-HDVC) may be adriving force for HEVC market adoption.

HEVC may include a number of coding tools, such as but not limited toextended video block sizes (e.g., up to 64×64), large transform sizes(e.g., up to 32×32), advanced motion vector prediction (AMVP), andsample adaptive offset (SAO) for improved coding efficiency. HEVC mayprovide support for parallelization, including tools such as but notlimited to Wavefront Parallel Processing (WPP) and tiles, in additionalto slice structure. When WPP and/or tiles are used, the video bitstreamcorresponding to one picture may be packetized into independentlydecodable subsets of bitstreams, but may not incur the additionaloverhead of slice headers. WPP and tiles may partition a picture intoregions to enable simultaneous decoding of these regions in parallel.

SUMMARY

Systems, methods, and instrumentalities are disclosed relating to regionof interest (ROI) video coding using tiles and tile groups. An encodedvideo sequence including a temporal series of pictures, a picture beingpartitioned into a plurality of tiles may be received. The plurality oftiles may be divided into at least one or more tile groups, providedthat not all the tiles representing the picture are members of the tilegroup. Signaling indicating parameters of the at least one or more tilegroup may be received. A tile group may be decoded and an ROI of apicture relating to the decoded tile group may be displayed. Only thetile group in the ROI may be decoded. The parameters of the at least oneor more tile groups may include the number of tile groups, a number oftiles in each tile group, and an index of each tile. The parameters ofthe at least one or more tile groups may be signaled in a pictureparameter set (PPS), video usability information (VUI), or asupplemental enhancement information (SEI) message. A tile group may beconstrained such that all pixels in the tile group are temporallypredicted from pixels in the same tile group in its reference pictures.

Signaling indicating a region of interest (ROI) may be received by thevideo decoder, or an ROI otherwise determined A ROI may be determined byeither a sender or a receiver, or negotiated between the sender and thereceiver. Signaling in the bitstream may be needed if the senderdetermines, or negotiates, the ROI. For example, a content provider mayidentify one or more regions of interest and may encode a representationof these ROI (spatial definition across time) into the bitstream itself(e.g., an ROI may be indicated through the pixel coordinates of itsvertices relative to the top left corner of the picture). At the decoderside, the available ROI may be presented to an end user in a userinterface, and the end user may select an ROI in order to view only thatregion. ROI information may also be transmitted outside the bitstream.In another example, a user interface may be provided which allows theend user to identify a region of interest in the displayed videocontent, the device may zoom to display the ROI, and such zooming maycause other areas of the video content to be excluded from the display.The ROI may correspond to the displayed picture and the displayedpicture may be a portion of the encoded video sequence. The entireencoded video sequence may not be decoded, but only the displayedpicture, or a tile group or tile groups overlapping the displayedpicture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of evenly partitioning apicture into tiles in the horizontal and the vertical dimensions.

FIG. 2 a is a diagram illustrating an example of an ROI contained within2 out of 4 tiles.

FIG. 2 b is a diagram illustrating an example of a block inside a ROI attime instance (T+1), but outside of the ROI at time instance (T).

FIG. 3 is a diagram illustrating an example of grouping tiles of apicture into more than one tile group.

FIG. 4 is a diagram illustrating an example of grouping a portion oftiles of a picture into one tile group, where another portion of thetiles do not belong to the tile group.

FIG. 5 is a diagram illustrating an example of a constraint on motionprediction of blocks in tile groups.

FIG. 6 is a diagram illustrating an example of a constraint on motionprediction of blocks in tile groups, even as the tile groups (and tiles)change shape.

FIG. 7 is a diagram illustrating an example of a constraint on motionprediction of blocks in tile groups, even as the tiles change shape anda tile group is added.

FIG. 8A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented.

FIG. 8B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 8A.

FIG. 8C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 8A.

FIG. 8D is a system diagram of another example radio access network andanother example core network that may be used within the communicationssystem illustrated in FIG. 8A.

FIG. 8E is a system diagram of another example radio access network andanother example core network that may be used within the communicationssystem illustrated in FIG. 8A.

DETAILED DESCRIPTION

A Region of Interest (ROI) refers to a portion of a picture in a videosequence, but not the entire picture, as described above. ROI coding maybe utilized for mobile video applications. For example, since mobiledevices may have a limited screen size, people may zoom into aparticular area of the video while watching, for example, by touching anarea of interest using a touchscreen, drawing a line or a box around anarea of interest using a pointer device, or by some other means. Videocontent may be produced for a different purpose than mobile usage (e.g.,TV broadcasting). Such content may be “re-purposed” for mobileapplications, such as but not limited to video streaming (e.g.,YouTube®, Hulu®, Amazon®, Netflix®, etc.). Automatic video resizing andretargeting may be utilized. Implementations described herein mayutilize tiles to provide ROI video coding that provides reduced decodingcomplexity.

Tiles may be supported by HEVC. Tiles may partition a picture intorectangular regions of certain sizes. FIG. 1 is a diagram illustratingan example of evenly partitioning a picture 100 in the horizontal andthe vertical dimensions into tiles 102 a, 102 b, 102 c, 102 d, 102 e,102 f, 102 g, 102 h, 102 i. Table 1 illustrates an example of a syntaxstructure for tiles in Picture Parameter Set (PPS) (e.g., in HEVC). If atiles_enabled_flag is turned on, then the number of tiles in eachdimension may be signaled. If the tiles are uniformly sized (e.g., ifuniform_spacing_flag is 1), then no additional information may besignaled. The width and height of the tiles may be signaled. Forexample, as shown in FIG. 1, num_tile_columns_minus1 andnum_tile_rows_minus1 may be set to 2 and uniform_spacing_flag may be setto 1. An additional flag loop_filter_across_tiles_enabled_flag may beused to indicate whether a deblocking filter will be applied across tileboundaries (e.g., a deblocking filter may be utilized to alleviatevisible discontinuity along the boundaries).

TABLE 1 Example of Signaling of Tiles in PPS pic_parameter_set_rbsp( ) {Descriptor . . . tiles_enabled_flag u(1)entropy_coding_sync_enabled_flag u(1) entropy_slice_enabled_flag u(1)if( tiles_enabled_flag ) { num_tile_columns_minus1 ue(v)num_tile_rows_minus1 ue(v) uniform_spacing_flag u(1) if(!uniform_spacing_flag ) { for( i = 0; i < num_tile_columns_minus1; i++ )column_width_minus1[ i ] ue(v) for( i = 0; i < num_tile_rows_minus1; i++) row_height_minus1[ i ] ue(v) } loop_filter_across_tiles_enabled_flagu(1) } . . . }An encoder may change how the tiles are partitioned from picture topicture by the encoder signaling a new PPS with new tile partitionparameters (Table 1). In one example, tiles need not remain equallysized compared to each other, or the same size compared to the same tileat an earlier instance; such that, if an ROI moves within a picturebetween two time instances, the encoder may signal a new PPS at thesecond time instance with new tile partition parameters that would allowthe ROI to remain within its current tile or tiles. If the tile groupmembership remains static, the encoder may not signal any new tile groupparameters.

FIG. 2 a is a diagram illustrating an example of a picture 200 in avideo sequence partitioned into (and coded as) tiles 202 a, 202 b, 202c, 202 d. An ROI 204 is contained within two of the tiles 202 a, 202 c.The tiles 202 a, 202 c that the ROI 204 overlaps may be said to coverthe ROI. The tiles 202 a, 202 b, 202 c, 202 d may be decodedindependently. When the picture 200 is being decoded, decoding the tilesthat the ROI 204 overlaps (e.g., the two tiles 202 a, 202 c) may besufficient for displaying the ROI of the picture on the screen.

All of the tiles 202 a, 202 b, 202 c, 202 d in the picture 200 may bedecoded even though a portion (e.g., only a portion) of the tiles (e.g.,tiles 202 a, 202 c) may need to be decoded for the ROI 204 to bedisplayed (e.g., if the picture 200 is a reference picture). HEVC mayuse temporal prediction to reduce temporal redundancy inherent in videosignals. All tiles (e.g., tiles 202 a, 202 b, 202 c, 202 d) in thepicture may be decoded such that the picture 200 may be used as areference picture to decode a subsequent picture in decoding order.

FIG. 2 b is a diagram illustrating an example of a picture 200 in avideo sequence partitioned into (and coded as) tiles 202 a, 202 b, 202c, 202 d at a time instance (T). An ROI 204 is contained within two ofthe tiles 202 a, 202 c. A video block 206 (e.g., a group of pixels) ispartially outside the ROI 204 at time instance (T). The block 206bridges tiles 202 a, 202 b at time instance (T).

It may be desirable to predict the block 206 at a time instance (T+1),and to do so, the picture 200 at time instance (T) may be used as areference picture to predict the picture 200 at time instance (T+1). TheROI may remain static. Since there may be no constraint in HEVC thatmotion estimation be confined within each of the tiles between thepicture being decoded (e.g., the picture 200 at time instance (T+1)) andone or more of its reference pictures (e.g., the picture 200 at timeinstance (T)), the video block 206 at time instance (T+1) may bepredicted from the video block 206 at time instance (T), if all of thetiles 202 a, 202 b, 202 c, 202 d in the reference picture at timeinstance (T) are decoded. The coding order may be the same as thedisplay order, or the coding order of pictures in a video sequence maybe different from the display order of pictures in a video sequence(e.g., the hierarchical B prediction structure).

Implementations are described herein for an encoder to put a constraintduring motion estimation to ensure that motion compensated predictionmay be performed within a subset of tiles that cover the ROI (e.g., thetiles 202 a, 202 c in the example of FIG. 2 b). Implementationsdescribed herein may facilitate reduced complexity ROI decoding.Implementations described herein may reduce decoding complexity andpower consumption, for example, by allowing a decoder to decode (e.g.,only decode) a subset of tiles covering the ROI within a series ofpictures in the temporal direction. Reduced decoding may be performed aslong as the subset of tiles covering the ROI remains the same, as willbe explained. This constraint may be signaled in the bitstream to informthe decoder that instead of full decoding (e.g., decoding of all of thetiles), reduced decoding (e.g., decoding a subset of the tiles) may beperformed.

Tile groups may be utilized. A tile may refer to a collection of pixelspel whose coordinates may be within the tile boundaries, bound_(left),bound_(right), bound_(top), bound_(bottom). For example,T={pel|coord_(x)(pel)∈[bound_(left), bound_(right)] andcoord_(y)(pel)∈[bound_(top), bound_(bottom)]}.

A tile group (TG) may refer to a combination of n tiles, TG={T₀, T₁, . .. T_(n−1)}, where T_(i), i=0 . . . n−1 may be tiles in a picture. Apixel sample pel may belong to a tile group TG if it belongs to a tilewithin the tile group. A tile group may satisfy the constraint(discussed herein) that motion compensated prediction may not go beyondits own boundaries. For example, if a pixel pel within a tile group TGin a picture is inter predicted, then it may be predicted (e.g., onlypredicted) from reference pixels within the same tile group TG in one ormore of the reference pictures. Pixels in a tile group may satisfy thefollowing constraint: If a reference pixel pel_ref in a referencepicture does not belong to a tile group TG, then it may not be used formotion compensated prediction of a pixel sample pel_cur in the (current)picture that belongs to the tile group TG.

FIG. 3 is a diagram illustrating an example of a picture 300 in a videosequence partitioned into (and coded as) tiles 302 a, 302 b, 302 c, 302d, 302 e, 302 f, 302 g, 302 h, 302 i, with grouping of the tiles intotile groups 303, 305. The first tile group 303 may include tiles 302 a,302 b, 302 d, 302 e. The second tile group 305 may include the remainingtiles 302 c, 302 f, 302 g, 302 h, 302 i.

FIG. 4 is a diagram illustrating an example of a picture 400 in a videosequence partitioned into (and coded as) tiles 402 a, 402 b, 402 c, 402d, 402 e, 402 f, 402 g, 402 h, 402 i, with only some tiles belonging toa tile group 403. For example, tiles 402 a, 402 b, 402 d, 402 e maybelong to the tile group 403 and the remaining tiles 402 c, 402 f, 402g, 402 h, 402 i in the picture may not belong to any tile group. Theremay not be a constraint on how the pixels in the areas covered by theremaining tiles 402 c, 402 f, 402 g, 402 h, 402 i may be predicted.

Although not illustrated in FIG. 3 or FIG. 4, a tile may belong to morethan one tile group. For example, if 302 a in FIG. 3 belongs to both 303and 305, that is, 303={302 a, 302 b, 302 d, 302 e} and 305={302 a, 302c, 302 f, 302 g, 302 h, 302 i}, then the pixels in 302 a may be motioncompensation predicted from the common area covered by 303 and 305,303∩305, namely, 302 a itself

FIG. 5 is a diagram illustrating an example of a picture 500 in a videosequence partitioned into (and coded as) tiles (not depicted forsimplicity of illustration) grouped into tile groups 503, 505 at a timeinstance (T). An ROI is not depicted for simplicity of illustration. TheROI may be represented by the tile group 503 or the tile group 505,although in practice, it is beneficial for the ROI to be slightlysmaller than the tile group that it overlaps. For example, the tilegroup 503 may additionally contain a small margin outside of the ROIsuch that, if loop_filter_across_tiles_enabled_flag in Table 1 is set to1, then in-loop filtering (e.g., deblocking filter, sample adaptiveoffset, and the like) may be performed along the tile boundaries withoutaffecting the pixel values inside of the ROI. A video block 506 iswithin tile group 503 at time instance (T). A video block 508 is withintile group 505 at time instance (T).

At a time instance (T+1), it may be desirable to predict the blocks 506,508 in the picture 500 at time instance (T+1) by using the picture 500at time instance (T) as a reference picture. A constraint is imposed onthe tile groups 503, 505. The video block 506 in the tile group 503 attime instance (T+1) may be predicted (e.g., only predicted) from areference block that lies entirely within the boundaries of the tilegroup 503. The video block 508 at time instance (T+1) in the tile group505 may be predicted (e.g., only predicted) from a reference block thatlies entirely within the boundaries of the tile group 505. “Lie entirelywithin” refers to situations where the pixels that participate in motioncompensated prediction, including motion interpolation due to fractionalpixel motion vectors, do not lie within any other tile group'sboundaries. This constraint may allow different tile groups to beindependently decodable in the temporal domain. If reduced decoding of aROI is desired, a first tile group may be defined to cover the ROI and asecond tile group, or no tile group, may be defined to cover the rest ofthe picture. Such a configuration may allow the decoder to decode (e.g.,only decode) the first tile group in a temporal series of pictures andbe able to display the ROI. Defining a tile group such that a ROI liesentirely within the tile group may allow a decoder to decode (e.g., onlydecode) a series of temporal pictures of that tile group to display theROI. Tiles in a picture may be partitioned into more than 2 tile groupsaccording to the application's need, for example, if there is more thanone ROI. Having more tiles groups may provide for more possibilities tosupport different ROIs. The constraint may be modified to allow pixelsfrom a tile that is a member of two tile groups to be predicted fromthat tile (see above).

As shown in Table 1, tile related parameters may be signaled in the PPSin HEVC. Within a video sequence, different pictures may be allowed touse different PPS's. The tile parameters may change from picture topicture in the same video sequence. Although in most video applicationsthe number of tiles and the locations of the tiles are likely to remainthe same within a video sequence (e.g., a series of pictures),situations may arise where not only the configuration of tiles may beallowed to change from picture to picture in the same video sequence,but also the grouping of tiles may be allowed to change from picture topicture.

FIG. 6 is a diagram illustrating an example of a picture 600 in a videosequence partitioned into (and coded as) tiles (not depicted forsimplicity of illustration) grouped into tile groups 603, 605 at a timeinstance (T). An ROI is not depicted for simplicity of illustration. Avideo block 606 is within tile group 603 at time instance (T). A videoblock 608 is within tile group 605 at time instance (T).

At a time instance (T+1), it may be desirable to predict the blocks 606,608 in the picture 600 by using the picture 600 at time instance (T) asa reference picture.

At a time instance (T+2), the tile groups 603, 605, have beenpartitioned differently from the picture 600 at time instance (T) andtime instance (T+1), e.g., from top and bottom to left and right,however, video block 606 continues to lie entirely within tile group603, and video block 608 continues to lie entirely within tile group605. This example of pictures in the same sequence with different shapesof tiles and tile groups nonetheless satisfies the motion-predictionconstraint discussed above, i.e., the blocks 606, 608 in the picture 600at time instance (T+2) may be predicted by using the picture 600 at timeinstance (T+1) as a reference picture. A PPS signal may be sent beforetime instance (T) defining the tiles and tile groups. Another PPS signalmay be sent between time instance (T+1) and time instance (T+2) definingthe tiles and tile groups.

FIG. 7 is a diagram illustrating an example of a picture 700 in a videosequence partitioned into (and coded as) tiles (depicted by a dottedline for simplicity of illustration) grouped into a tile group 703 at atime instance (T). An ROI is not depicted for simplicity ofillustration. A video block 706 is within tile group 703 at timeinstance (T). A video block 708 is also within tile group 703 at timeinstance (T).

At a time instance (T+1), it may be desirable to predict the blocks 706,708 in the picture 700 by using the picture 700 at time instance (T) asa reference picture.

At a time instance (T+2), the tile group 703 has been partitioneddifferently from the picture 700 at time instance (T) and time instance(T+1), and a new tile group 705 is created. Video block 706 continues tolie entirely within tile group 703. Video block 708 now lies within newtile group 705. This is an example illustrating different shapes oftiles and tile groups, and different numbers of tile groups, atdifferent time instances. The tile group constraint described herein maydictate that, for time instances (T+2), (T+3), video block 706 may bepredicted from tile group 703 at time instances (T), (T+1). Since tilegroup 703 may cover the entire picture at time instances (T), (T+1),there may be less restriction on motion compensated prediction (e.g.,with the exception of some boundary conditions). Since tile group 705did not exist at time instances (T), (T+1), for time instance (T+2), thevideo block 708 may not be constrained and may be predicted fromanywhere in the picture. For time instance (T+3), the video block 708may be predicted from anywhere in the picture at time instances (T),(T+1) (i.e., without any constraint), or it may be predicted from withintile group 705 at time instance (T+2).

Although not shown in FIG. 4 through FIG. 7, tile groups may consist oftiles that may or may not be spatially contiguous.

Tile groups may be signaled using the syntax in Table 2. The number oftile groups in the picture may be signaled first. For each tile group,the number of tiles included within a picture may be signaled. Eachindex of the tiles in the group may be signaled. The raster scan ordermay be used to index the tiles in a picture. The tiles in a tile groupmay have disjoint indexes and/or may be spatially disjoint. Variouscoding implementations may be applied to code the values of the syntaxelements (e.g., as shown in Table 2). For example, ue(v) (ExponentialGolomb code) and/or u(v) (fixed length coding) may be used. The valuesof the syntax elements (e.g., as shown in Table 2) may be bounded by thenumber of tiles in a picture. The number of bits may be determinedaccordingly if u(v) is used.

TABLE 2 Example of Tiles Groups tile_group ( ) { Descriptornum_tile_groups_minus1 u(v) or ue(v) for( i = 0; i <=num_tile_groups_minus1; i++ ) { num_tiles_in_group_minus1[ i ] u(v) orue(v) for( j = 0; j <= num_tiles_in_group_minus1[ i ]; i++ ) tile_index[i ][j ] u(v) or ue(v) } } }

Different implementations may be utilized to incorporate the tile groupsyntax element into a video bitstream. Tile related parameters may besignaled in the PPS (e.g., as shown in Table 1). Tile group parameters(e.g., as shown in Table 2) may be signaled in the PPS (e.g., after thetile parameters are sent).

The tile groups may be signaled in Video Usability Information (VUI).VUI may be present as part of the Sequence Parameter Set (SPS). VUI maybe used to convey a range of information to the receiver, such as butnot limited to bitstream conformance, color space information, andbitstream constraints. VUI may include syntax elements that may be usedto put a restriction on the usage of tiles in the bitstream. Forexample, tiles_fixed_structure_flag may be used in VUI.tiles_fixed_structure_flag may dictate whether a composition of tilesmay change from picture to picture in the same video sequence.tiles_fixed_structure_flag may dictate whether one or more active PPS'sin the same sequence may have different tile parameters. The examplesprovided in FIG. 6 and FIG. 7 may exist if tiles_fixed_structure_flag isset to 0. The tile group parameters may be signaled as part of the VUI,for example, as shown in Table 3.

TABLE 3 Example of Signaling Tile Group in VUI De- scrip- tile_group ( ){ tor . . . bitstream_restriction_flag u(1) if(bitstream_restriction_flag ) { tiles_fixed_structure_flag u(1)num_tile_groups_minus1 u(v) or ue(v) for( i = 0; i <=num_tile_groups_minus1; i++ ) { num_tiles_in_group_minus1[i] u(v) orue(v) for( j = 0; j <=num_tiles_in_group_minus1[ i ]; i++ ) tile_index[i ][ j ] u(v) or ue(v) } motion_vectors_over_pic_boundaries_flag u(1) .. . } u(v) or ue(v) . . . }

Tile group signaling may be provided via SEI messages. HEVC may define aset of Supplemental Enhancement Information (SEI) messages to conveysupplemental information for various purposes. The SEI messages mayprovide useful information about the video to facilitate certainoperations at the receiver side, although the messages may not beessential to the decoding process itself. For example, a displayorientation SEI message (e.g., SEI payload type 47) may be used toinform the decoder about the orientation of one or more pictures in thevideo sequence (e.g., in HEVC). The client device may use an orientationSEI message to rotate the pictures as needed to ensure that the usersmay see the video in the correct orientation. If the orientation SEImessage is not used, the bitstream may still be correctly decoded, butone or more of the pictures in the sequence may be displayed incorrectly(e.g., one or more pictures may be upside down, rotated by 90 degreesclock- or counter clock-wise, etc.). If a tile group(s) is signaled asSEI message, then a SEI payload type may be assigned to the tilegroup(s), for example, followed by syntax elements (e.g., as shown inTable 2).

Implementations utilizing tile groups and ROI coding to reduce decodingcomplexity may be described herein. Implementations may utilize tilegroups and ROI coding to skip the decoding of one or more tile groupsthat may not overlap with the ROI. Tile groups may be used to furtheraccelerate parallel decoding in finer granularity. For example, whenmulti-threaded decoding is performed using tiles, without tile groups,reference picture decoding may be synchronized at the picture levelamong different tiles. This may be because decoding of a tile in thesubsequent picture may need to reference the entire reference picture.If tile groups are enabled, then reference picture decoding may besynchronized at the tile group level (e.g., which may be equivalent tothe sub picture level). This may allow a decoder to better coordinatedecoding load among the threads.

FIG. 8A is a diagram of an example communications system 800 in whichone or more disclosed embodiments may be implemented. The communicationssystem 800 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 800 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems800 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 8A, the communications system 800 may include wirelesstransmit/receive units (WTRUs) 802 a, 802 b, 802 c, 802 d, a radioaccess network (RAN) 803/804/805, a core network 806/807/809, a publicswitched telephone network (PSTN) 808, the Internet 810, and othernetworks 812, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations, networks,and/or network elements. Each of the WTRUs 802 a, 802 b, 802 c, 802 dmay be any type of device configured to operate and/or communicate in awireless environment. By way of example, the WTRUs 802 a, 802 b, 802 c,802 d may be configured to transmit and/or receive wireless signals andmay include user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, or any other terminal capableof receiving and processing compressed video communications.

The communications systems 800 may also include a base station 814 a anda base station 814 b. Each of the base stations 814 a, 814 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 802 a, 802 b, 802 c, 802 d to facilitate access to one or morecommunication networks, such as the core network 806/807/809, theInternet 810, and/or the networks 812. By way of example, the basestations 814 a, 814 b may be a base transceiver station (BTS), a Node-B,an eNode B, a Home Node B, a Home eNode B, a site controller, an accesspoint (AP), a wireless router, and the like. While the base stations 814a, 814 b are each depicted as a single element, it will be appreciatedthat the base stations 814 a, 814 b may include any number ofinterconnected base stations and/or network elements.

The base station 814 a may be part of the RAN 803/804/805, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 814 a and/or the base station814 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 814 a may be dividedinto three sectors. Thus, in one embodiment, the base station 814 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 814 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 814 a, 814 b may communicate with one or more of theWTRUs 802 a, 802 b, 802 c, 802 d over an air interface 815/816/817,which may be any suitable wireless communication link (e.g., radiofrequency (RF), microwave, infrared (IR), ultraviolet (UV), visiblelight, etc.). The air interface 815/816/817 may be established using anysuitable radio access technology (RAT).

More specifically, as noted above, the communications system 800 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 814 a in the RAN 803/804/805 and the WTRUs 802a, 802 b, 802 c may implement a radio technology such as UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA),which may establish the air interface 815/816/817 using wideband CDMA(WCDMA). WCDMA may include communication protocols such as High-SpeedPacket Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may includeHigh-Speed Downlink Packet Access (HSDPA) and/or High-Speed UplinkPacket Access (HSUPA).

In another embodiment, the base station 814 a and the WTRUs 802 a, 802b, 802 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface815/816/817 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 814 a and the WTRUs 802 a, 802 b,802 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 814 b in FIG. 8A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 814 b and the WTRUs 802 c, 802 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 814 band the WTRUs 802 c, 802 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 814 b and the WTRUs 802 c, 802 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 8A,the base station 814 b may have a direct connection to the Internet 810.Thus, the base station 814 b may not be required to access the Internet810 via the core network 806/807/809.

The RAN 803/804/805 may be in communication with the core network 806,which may be any type of network configured to provide voice, data,applications, and/or voice over internet protocol (VoIP) services to oneor more of the WTRUs 802 a, 802 b, 802 c, 802 d. For example, the corenetwork 806/807/809 may provide call control, billing services, mobilelocation-based services, pre-paid calling, Internet connectivity, videodistribution, etc., and/or perform high-level security functions, suchas user authentication. Although not shown in FIG. 8A, it will beappreciated that the RAN 803/804/805 and/or the core network 806/807/809may be in direct or indirect communication with other RANs that employthe same RAT as the RAN 803/804/805 or a different RAT. For example, inaddition to being connected to the RAN 803/804/805, which may beutilizing an E-UTRA radio technology, the core network 806/807/809 mayalso be in communication with another RAN (not shown) employing a GSMradio technology.

The core network 806/807/809 may also serve as a gateway for the WTRUs802 a, 802 b, 802 c, 802 d to access the PSTN 808, the Internet 810,and/or other networks 812. The PSTN 808 may include circuit-switchedtelephone networks that provide plain old telephone service (POTS). TheInternet 810 may include a global system of interconnected computernetworks and devices that use common communication protocols, such asthe transmission control protocol (TCP), user datagram protocol (UDP)and the internet protocol (IP) in the TCP/IP internet protocol suite.The networks 812 may include wired or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 812 may include another core network connected to one or moreRANs, which may employ the same RAT as the RAN 803/804/805 or adifferent RAT.

Some or all of the WTRUs 802 a, 802 b, 802 c, 802 d in thecommunications system 800 may include multi-mode capabilities, i.e., theWTRUs 802 a, 802 b, 802 c, 802 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 802 c shown in FIG. 8A may be configured tocommunicate with the base station 814 a, which may employ acellular-based radio technology, and with the base station 814 b, whichmay employ an IEEE 802 radio technology.

FIG. 8B is a system diagram of an example WTRU 802. As shown in FIG. 8B,the WTRU 802 may include a processor 818, a transceiver 820, atransmit/receive element 822, a speaker/microphone 824, a keypad 826, adisplay/touchpad 828, non-removable memory 830, removable memory 832, apower source 834, a global positioning system (GPS) chipset 836, andother peripherals 838. It will be appreciated that the WTRU 802 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment. Also, embodiments contemplate that thebase stations 814 a and 814 b, and/or the nodes that base stations 814 aand 814 b may represent, such as but not limited to transceiver station(BTS), a Node-B, a site controller, an access point (AP), a home node-B,an evolved home node-B (eNodeB), a home evolved node-B (HeNB), a homeevolved node-B gateway, and proxy nodes, among others, may include someor all of the elements depicted in FIG. 1B and described herein.

The processor 818 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), agraphics processing unit (GPU), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Array (FPGAs) circuits, any other type of integratedcircuit (IC), a state machine, and the like. The processor 818 mayperform signal coding, data processing, power control, input/outputprocessing, and/or any other functionality that enables the WTRU 802 tooperate in a wireless environment. The processor 818 may be coupled tothe transceiver 820, which may be coupled to the transmit/receiveelement 822. While FIG. 8B depicts the processor 818 and the transceiver820 as separate components, it will be appreciated that the processor818 and the transceiver 820 may be integrated together in an electronicpackage or chip.

The transmit/receive element 822 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 814a) over the air interface 815/816/817. For example, in one embodiment,the transmit/receive element 822 may be an antenna configured totransmit and/or receive RF signals. In another embodiment, thetransmit/receive element 822 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet another embodiment, the transmit/receive element 822 may beconfigured to transmit and receive both RF and light signals. It will beappreciated that the transmit/receive element 822 may be configured totransmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element 822 is depicted inFIG. 8B as a single element, the WTRU 802 may include any number oftransmit/receive elements 822. More specifically, the WTRU 802 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 802 mayinclude two or more transmit/receive elements 822 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 815/816/817.

The transceiver 820 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 822 and to demodulatethe signals that are received by the transmit/receive element 822. Asnoted above, the WTRU 802 may have multi-mode capabilities. Thus, thetransceiver 820 may include multiple transceivers for enabling the WTRU802 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 818 of the WTRU 802 may be coupled to, and may receiveuser input data from, the speaker/microphone 824, the keypad 826, and/orthe display/touchpad 828 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor818 may also output user data to the speaker/microphone 824, the keypad826, and/or the display/touchpad 828. In addition, the processor 818 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 830 and/or the removable memory 832.The non-removable memory 830 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 832 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 818 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 802, such as on a server or a home computer (notshown).

The processor 818 may receive power from the power source 834, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 802. The power source 834 may be any suitabledevice for powering the WTRU 802. For example, the power source 834 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 818 may also be coupled to the GPS chipset 836, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 802. In additionto, or in lieu of, the information from the GPS chipset 836, the WTRU802 may receive location information over the air interface 815/816/817from a base station (e.g., base stations 814 a, 814 b) and/or determineits location based on the timing of the signals being received from twoor more nearby base stations. It will be appreciated that the WTRU 802may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 818 may further be coupled to other peripherals 838, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 838 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 8C is a system diagram of the RAN 803 and the core network 806according to an embodiment. As noted above, the RAN 803 may employ aUTRA radio technology to communicate with the WTRUs 802 a, 802 b, 802 cover the air interface 815. The RAN 804 may also be in communicationwith the core network 806. As shown in FIG. 8C, the RAN 803 may includeNode-Bs 840 a, 840 b, 840 c, which may each include one or moretransceivers for communicating with the WTRUs 802 a, 802 b, 802 c overthe air interface 815. The Node-Bs 840 a, 840 b, 840 c may each beassociated with a particular cell (not shown) within the RAN 803. TheRAN 803 may also include RNCs 842 a, 842 b. It will be appreciated thatthe RAN 803 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 8C, the Node-Bs 840 a, 840 b may be in communicationwith the RNC 842 a. Additionally, the Node-B 840 c may be incommunication with the RNC 842 b. The Node-Bs 840 a, 840 b, 840 c maycommunicate with the respective RNCs 842 a, 842 b via an Iub interface.The RNCs 842 a, 842 b may be in communication with one another via anIur interface. Each of the RNCs 842 a, 842 b may be configured tocontrol the respective Node-Bs 840 a, 840 b, 840 c to which it isconnected. In addition, each of the RNCs 842 a, 842 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 806 shown in FIG. 8C may include a media gateway (MGW)844, a mobile switching center (MSC) 846, a serving GPRS support node(SGSN) 848, and/or a gateway GPRS support node (GGSN) 850. While each ofthe foregoing elements are depicted as part of the core network 806, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 842 a in the RAN 803 may be connected to the MSC 846 in the corenetwork 806 via an IuCS interface. The MSC 846 may be connected to theMGW 844. The MSC 846 and the MGW 844 may provide the WTRUs 802 a, 802 b,802 c with access to circuit-switched networks, such as the PSTN 808, tofacilitate communications between the WTRUs 802 a, 802 b, 802 c andtraditional land-line communications devices.

The RNC 842 a in the RAN 803 may also be connected to the SGSN 848 inthe core network 806 via an IuPS interface. The SGSN 848 may beconnected to the GGSN 850. The SGSN 848 and the GGSN 850 may provide theWTRUs 802 a, 802 b, 802 c with access to packet-switched networks, suchas the Internet 810, to facilitate communications between and the WTRUs802 a, 802 b, 802 c and IP-enabled devices.

As noted above, the core network 806 may also be connected to thenetworks 812, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 8D is a system diagram of the RAN 804 and the core network 807according to another embodiment. As noted above, the RAN 804 may employan E-UTRA radio technology to communicate with the WTRUs 802 a, 802 b,802 c over the air interface 816. The RAN 804 may also be incommunication with the core network 807.

The RAN 804 may include eNode-Bs 860 a, 860 b, 860 c, though it will beappreciated that the RAN 804 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 860 a, 860 b, 860c may each include one or more transceivers for communicating with theWTRUs 802 a, 802 b, 802 c over the air interface 816. In one embodiment,the eNode-Bs 860 a, 860 b, 860 c may implement MIMO technology. Thus,the eNode-B 860 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 802 a.

Each of the eNode-Bs 860 a, 860 b, 860 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 8D, theeNode-Bs 860 a, 860 b, 860 c may communicate with one another over an X2interface.

The core network 807 shown in FIG. 8D may include a mobility managementgateway (MME) 862, a serving gateway 864, and a packet data network(PDN) gateway 866. While each of the foregoing elements are depicted aspart of the core network 807, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 862 may be connected to each of the eNode-Bs 860 a, 860 b, 860 cin the RAN 804 via an S1 interface and may serve as a control node. Forexample, the MME 862 may be responsible for authenticating users of theWTRUs 802 a, 802 b, 802 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 802 a,802 b, 802 c, and the like. The MME 862 may also provide a control planefunction for switching between the RAN 804 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 864 may be connected to each of the eNode Bs 860 a,860 b, 860 c in the RAN 804 via the S1 interface. The serving gateway864 may generally route and forward user data packets to/from the WTRUs802 a, 802 b, 802 c. The serving gateway 864 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 802 a,802 b, 802 c, managing and storing contexts of the WTRUs 802 a, 802 b,802 c, and the like.

The serving gateway 864 may also be connected to the PDN gateway 866,which may provide the WTRUs 802 a, 802 b, 802 c with access topacket-switched networks, such as the Internet 810, to facilitatecommunications between the WTRUs 802 a, 802 b, 802 c and IP-enableddevices.

The core network 807 may facilitate communications with other networks.For example, the core network 807 may provide the WTRUs 802 a, 802 b,102 c with access to circuit-switched networks, such as the PSTN 808, tofacilitate communications between the WTRUs 802 a, 802 b, 802 c andtraditional land-line communications devices. For example, the corenetwork 807 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 807 and the PSTN 808. In addition, the corenetwork 807 may provide the WTRUs 802 a, 802 b, 802 c with access to thenetworks 812, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 8E is a system diagram of the RAN 805 and the core network 809according to another embodiment. The RAN 805 may be an access servicenetwork (ASN) that employs IEEE 802.16 radio technology to communicatewith the WTRUs 802 a, 802 b, 802 c over the air interface 817. As willbe further discussed below, the communication links between thedifferent functional entities of the WTRUs 802 a, 802 b, 802 c, the RAN805, and the core network 809 may be defined as reference points.

As shown in FIG. 8E, the RAN 805 may include base stations 880 a, 880 b,880 c, and an ASN gateway 882, though it will be appreciated that theRAN 805 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 880 a, 880 b,880 c may each be associated with a particular cell (not shown) in theRAN 805 and may each include one or more transceivers for communicatingwith the WTRUs 802 a, 802 b, 802 c over the air interface 817. In oneembodiment, the base stations 880 a, 880 b, 880 c may implement MIMOtechnology. Thus, the base station 880 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 802 a. The base stations 880 a, 880 b, 880 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 882 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 809, and the like.

The air interface 817 between the WTRUs 802 a, 802 b, 802 c and the RAN805 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 802 a, 802 b, 802 cmay establish a logical interface (not shown) with the core network 809.The logical interface between the WTRUs 802 a, 802 b, 802 c and the corenetwork 809 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 880 a, 880 b,880 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 190 a, 880 b,880 c and the ASN gateway 882 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs802 a, 802 b, 800 c.

As shown in FIG. 8E, the RAN 805 may be connected to the core network809. The communication link between the RAN 805 and the core network 809may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 809 may include a mobile IP home agent(MIP-HA) 884, an authentication, authorization, accounting (AAA) server886, and a gateway 888. While each of the foregoing elements aredepicted as part of the core network 809, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA 884 may be responsible for IP address management, and mayenable the WTRUs 802 a, 802 b, 802 c to roam between different ASNsand/or different core networks. The MIP-HA 884 may provide the WTRUs 802a, 802 b, 802 c with access to packet-switched networks, such as theInternet 810, to facilitate communications between the WTRUs 802 a, 802b, 802 c and IP-enabled devices. The AAA server 886 may be responsiblefor user authentication and for supporting user services. The gateway888 may facilitate interworking with other networks. For example, thegateway 888 may provide the WTRUs 802 a, 802 b, 802 c with access tocircuit-switched networks, such as the PSTN 808, to facilitatecommunications between the WTRUs 802 a, 802 b, 802 c and traditionalland-line communications devices. In addition, the gateway 888 mayprovide the WTRUs 802 a, 802 b, 802 c with access to the networks 812,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 8E, it will be appreciated that the RAN 805may be connected to other ASNs and the core network 809 may be connectedto other core networks. The communication link between the RAN 805 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 802 a, 802 b, 802 cbetween the RAN 805 and the other ASNs. The communication link betweenthe core network 809 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, UE, terminal, base station, RNC, and/or any host computer.

1. An encoder for encoding a video sequence, comprising: a processor,wherein the processor encodes the video sequence, such that theprocessor: partitions a picture contained in the video sequence intotiles; groups at least one tile into at least one tile group, providedthat not all the tiles representing the picture are members of the atleast one tile group; and constrains motion compensated prediction ineach tile group of the at least one tile group, such that motioncompensated prediction of pixels in the tile group must not usereference pixels spatially located outside of the tile group.
 2. Theencoder of claim 1, wherein at least two tiles are in the at least onetile group, and the tiles are not spatially contiguous.
 3. The encoderof claim 1, wherein the tile belongs to at least two tile groups.
 4. Theencoder of claim 1, wherein the encoder sends signaling indicatingparameters of the at least one tile group.
 5. The encoder of claim 4,wherein the parameters comprise the number of tile groups, the number oftiles in each tile group, and an index of each tile in each tile group.6. The encoder of claim 5, wherein the index of a tile indicates thelocation of the tile among all tiles in the picture in raster scanorder.
 7. The encoder of claim 5, wherein the encoder signals theparameters in a picture parameter set (PPS), video usability information(VUI), or a supplemental enhancement information (SEI) message.
 8. Theencoder of claim 4, wherein the encoder signals the parameters in asupplemental enhancement information (SEI) message.
 9. A receiver forreceiving an encoded video sequence, comprising: determining a region ofinterest (ROI) in the encoded video sequence; receiving a video sequencewhich defines at least one tile group overlapping the ROI, selecting anddecoding the at least one tile group based on this signaling, anddisplaying a picture relating to the decoded at least one tile group.10. The receiver of claim 9, further comprising decoding according to aconstraint that motion compensated prediction in the at least one tilegroup covering the ROI must not use reference pixels spatially locatedoutside of the at least one tile group.
 11. The receiver of claim 9,wherein only the at least one tile group overlapping the ROI is decoded.12. The receiver of claim 9, wherein tiles outside the decoded at leastone tile group are not decoded.
 13. A method comprising: receiving anencoded video sequence, selecting a region of interest (ROI) within thevideo sequence; and decoding the ROI without decoding the entire videosequence.
 14. The method of claim 13, wherein the encoded video sequencecomprises a plurality of tiles, the plurality of tiles divided into oneor more tile groups, at least one of the tile groups overlapping theROI, wherein the ROI is smaller than the set of one or more tile groupsthat it overlaps.
 15. The method of claim 14, wherein only the one ormore tile groups that overlap the ROI are decoded.
 16. The method ofclaim 15, further comprising decoding according to a constraint thatmotion compensated prediction in a tile group at a current time instancebelonging to the one or more the tile groups overlapping the ROI mustnot use reference pixels spatially located outside of the tile group.17. The method of claim 14, wherein the configuration of at least one ofthe tiles changes spatially over time.
 18. The method of claim 14,wherein the configuration of at least one of the tile groups changesspatially over time.
 19. The method of claim 14, wherein the number oftile groups changes over time.
 20. A method comprising: partitioning apicture within the encoded video sequence into tiles, and sending anencoded video sequence with signaling indicating parameters in asupplemental enhancement information (SEI) message defining at least onetile group, the number of tiles in the tile group, and an index of eachtile in the tile group, such that a user may select a region of interest(ROI) within the video sequence and display the ROI, provided that thegroup of tiles overlapping the ROI are decoded and displayed, and thetiles not overlapping the ROI are not decoded.